Hours after Donald Trump's lackies in Congress lost their majority in the House of Representatives, Trump dealt a huge blow to Special Council Robert Mueller's investigation into Trump's ties to Russia. He put someone who has openly trashed the investigation in charge of it.

This afternoon, Trump fired Attorney General Jeff Sessions. Then, he put Matthew Whitaker in charge of the Mueller investigation – giving him the final say on the scope, budget and indictments.

Make no mistake: This is a Constitutional crisis in the making.

Tomorrow evening, people across the country are coming together to stop this attack on our democracy. There are already over 900 events scheduled. This is your chance to demand action to correct this injustice. Will you join us?

Trump likely fired Mueller because he's getting nervous -- he knows that the Justice Department is closing in on him. Mueller may even be looking at Trump's potential obstruction of justice.

Earlier this year, four of Trump's associates, including his longtime personal lawyer Michael Cohen -- the same man who paid $130,000 to hush up Stormy Daniels -- pleaded guilty to charges that stemmed from Mueller's investigation. These included lying to the FBI and campaign finance violations.

What's more, Paul Manafort, former chairman of Trump's presidential campaign, pleaded guilty to eight counts of tax and bank fraud in August. And now, former Trump campaign advisor Roger Stone has been subpoenaed and is under serious investigation.

Trump can feel the walls closing in – and he wants to distract from the Democrats' electoral victories across the country last night. We can't let him get away with it.

Under any other circumstances, we'd be celebrating the firing of Jeff Sessions. Sessions used his position as Attorney General to attack voting rights, gut protections for transgender students, and separate immigrant children from their families.

But let's be clear: Trump didn't fire Sessions because Sessions was advancing an agenda of racism and hate. He fired Sessions as the first step toward stopping the Mueller investigation.

Congress has the Constitutional authority and obligation to hold Trump accountable for this abuse of power. But we've seen Republicans in Congress give Trump pass after pass every time he crosses another line.

If they don't step up now to hold Trump accountable, they may never act. And if they don't act, we could be facing a constitutional crisis. With many new leaders coming to Congress in January, it's critical that we send a strong message now that standing by and allowing Donald Trump to slide the U.S. into authoritarianism is unacceptable.

We've seen it all around the world -- when strongman leaders take over and corruption runs rampant, people and the planet suffer.

If we want to defend and expand our environmental protections, we need a strong and healthy democracy. We can't let Trump undermine it.

This is a defining moment for Congress. Will our Representatives fight back in the face of corruption?

Or will they let Trump stamp out our core governing principles while they stand by and do nothing?

If people like you stay silent, your elected officials will cave to their political instincts, and Trump will get away with attacking our system of government. So we need you to demand that they defend our democracy from Trump's worst authoritarian instincts.